The present invention generally relates to carriage mechanisms for printers, and more particularly to a carriage mechanism for a printer in which a printing operation and an operation of taking up an ink ribbon are carried out when a printing head is in a printing position and the printing operation is interrupted when the printing head is in a non-printing position.
Conventionally, there is a thermal printer which carries out a printing operation by melting ink coated on an ink ribbon by heating elements of a thermal printing head (hereinafter simply referred to as a head) and transferring the melted ink on a recording paper. In such a thermal printer, the printing operation is carried out when the head is in a printing position where the head is in contact with the ink ribbon and can transfer the ink of the ink ribbon on the recording paper. A carriage which is provided with the head is successively moved in a printing direction and the ink ribbon is taken up by a predetermined quantity every time a predetermined quantity of printing is completed. For example, when returning the carriage to a set position where the next printing operation is to be started, the head is first moved to a non-printing position where the head is separated from the ink ribbon before moving the carriage.
In the conventional thermal printer, the ink ribbon is taken up by use of a motor provided exclusively for taking up the ink ribbon, and the head is moved between the printing and non-printing positions by use of a solenoid plunger and the like. In other words, the taking up of the ink ribbon and the moving of the head are performed by use of independent driving devices. As a result, there are problems in that the construction of the printer is complex, the construction of a driving and controlling system is complex because of the need to independently control the driving devices for the ink ribbon and the head, and the printer as a whole is expensive.
In addition, in the conventional thermal printer, it is difficult to adjust a contact force of the head on the ink ribbon and the recording paper when carrying out the printing operation by moving the head to the printing position. For this reason, there are problems in that an unwanted printing operation may be carried out erroneously and a large contact noise may be generated. Furthermore, when moving the head to the non-printing position and then moving the carriage, there is a problem in that the ink ribbon may rub the recording paper as the carriage is moved when the head is not completely separated from the ink ribbon due to breakdown of the solenoid plunger and the like.